1. Field of the Invention
The present invention relates to hinge assemblies and, particularly, to hinge assemblies for foldable electronic devices, such as mobile phones and portable computers.
2. Description of Related Art
Presently, perhaps the most popular portable electronic device in the marketplace is the foldable mobile phone, which generally includes a cover section and a body section. The cover section and the body section are rotatably interconnected through a hinge assembly, for switching the telephone between an in-use position and a closed position.
One kind of hinge assembly employs a cam and a follower, which makes the cover section fold outward from the body section and then holds the cover section in the open position. The hinge assembly typically includes a shaft, a rotatable element, and a spring. The shaft has a thread thereon, and the rotatable element forms a protrusion. When assembled, the rotatable element is placed on the shaft and the protrusion engages with the thread of the shaft. The spring is placed around the shaft, and resists the rotatable element. The rotatable element may rotate and slide along the thread under the pressing force of the spring.
However, although the hinge assembly may achieve the opening and closing of the foldable electronic device, forming the thread on the shaft is complicated and expensive. In addition, the thread is directly machined on the shaft. The material of the shaft and the thread is the same so the property of the thread cannot satisfy resist-abraded requirement. The threads can easily be damaged. The damage may eventually lead to premature malfunction or failure of the foldable electronic device.
Therefore, a new hinge assembly is desired in order to overcome the above-described shortcoming.